What you must know to protect yourself against the new crop of hazardous weight loss pills

If you wanted to lose weight last year, you might have been tempted to try Slimming Beauty Bitter Orange Slimming Capsules, a weight loss dietary supplement sold on the Internet. The label claimed that Slimming Beauty was "100% herbal" and "a natural vitamin and calcium" capsule for use even by children as young as 2. But the label didn't have two important warnings: First, that Slimming Beauty was illegally spiked with dangerous amounts of sibutramine, a powerful prescription-strength stimulant. Second, if you had tried it, you could have had a heart attack.

If the word sibutramine sounds familiar, that's because it's the generic name for Meridia, the prescription weight loss drug withdrawn from the market last October at the FDA's request. Though the agency had approved the drug in 1997, a recent 10,000-patient, 6-year study showed that sibutramine upped the risk of nonfatal "cardiovascular events" like heart attacks and strokes by 16%, causing the FDA to reconsider.

The same day the FDA announced the Meridia recall, it also issued a consumer warning against Slimming Beauty, citing several reports of serious side effects, including elevated blood pressure, headaches, vomiting, and insomnia. But unfortunately, the FDA doesn't have as much regulatory power over supplements as it does over drugs: It can't require intensive clinical trials before one of these products goes on the market, and it must run its own tests to prove that a supplement contains dangerous illegal drugs before it can try to remove it. Even then, there are so many similar products on the Internet that it's often unclear who actually manufactures a spiked supplement—as was the case with Slimming Beauty. After the FDA alert, the product vanished into cyberspace, but sibutramine—and other potentially dangerous substances—may still be lurking in other dietary supplements available to anyone with a Web browser and a credit card.

"Dietary supplements may represent the next big drug safety catastrophe," says Steven Nissen, MD, a cardiologist at the Cleveland Clinic and a Prevention advisory board member. "We don't know exactly what most supplements contain, so we don't know if they're actually safe." More and more, weight loss products—along with supplements that purport to treat sexual dysfunction or enhance athletic performance—are being "adulterated" with potentially dangerous ingredients by their manufacturers. "Originally, the makers would throw in something like caffeine to give you a kick," says Tod Cooperman, MD, president of ConsumerLab.com. "Now they're adding in compounds you find in prescription drugs without including that information on their labels." Some of these products—which are most often sold on the Internet so the manufacturers can evade regulators—may include versions of Meridia, Viagra, Cialis, or Levitra without consumers' knowledge.

The other thing consumers don't realize is that adulterated products can be far riskier than prescription diet pills. If you'd had a prescription for Meridia, for instance, you would have been under a doctor's care and would have been aware of how much sibutramine you were taking, as well as what side effects you might expect, because they were listed on the label. But in the virtually unregulated world of weight loss supplements, there's no way to know definitively what you're getting, how much—or what it can do to you.

In recent years, the FDA has gone after more than 70 tainted weight loss products, many with names like Slim Burn, 24 Hours Diet, and Natural Model, after finding that they had been adulterated with undeclared stimulants, diuretics, and antidepressants, often in amounts exceeding the maximum recommended dosages at which such drugs can be prescribed.

Sometimes the additives aren't legal even with a prescription. For example, one supplement targeted by the FDA contained fenproporex, a stimulant not approved in the United States because it can cause arrhythmia and possibly even sudden death.

In addition, these products often are not effective for the conditions for which they're advertised and may divert patients from legitimate medications, according to Dr. Nissen. If they do seem to be making a difference, that may be cause for concern, too. "If a weight loss supplement is working, it could be due to a stimulant whose safety is unproven," says Arthur Agatston, MD, a cardiologist and member of the Prevention advisory board. "Even if you lose weight, you may have unpleasant, even dangerous cardiac side effects."

"People who are overweight or obese are desperate to lose weight and vulnerable to snake oil salesmen pitching weight loss products," says Dr. Nissen. "Sadly, action may not get taken until there is a high-profile death." As far as the FDA knows, no one died after taking Slimming Beauty, but dangerous products often slide under the radar—until there's a disaster. Although the FDA is nominally charged with the safety of supplements, its ability to police them is limited by the size of the industry, the scope of the FDA's other duties, and the fact that the agency is not empowered to subject supplements to the same kind of scrutiny it gives to drugs—especially before they go on the market.

"The reality is that we are lacking resources in terms of authority, manpower, and money," admits Siobhan DeLancey, an FDA spokesperson. With an already tight budget, "we allocate our funds to best protect the public health, focusing on issues like foodborne illnesses that are causing serious illness and death," she explains.

The problem would be significant even if the FDA were better equipped. Expert estimates of the number of supplements range from 40,000 to nearly 75,000 products, including everything from vitamin C to items like Slimming Beauty. Supplement makers are required to register with the FDA—and the Council for Responsible Nutrition's president and CEO, Steve Mister, asserts that all legitimate ones who make safe products do—but the agency concedes that there are so many it can't keep track of them all. And makers of adulterated supplements may not register at all: "Anyone can set up a Web page and put a US address on it," DeLancey says. "This is a group of individuals that's willfully operating outside the law."

Cracking down on supplements' fraudulent and exaggerated advertising is the responsibility of the Federal Trade Commission. But again, resources are scant. "When you have thousands of products and hundreds of thousands of advertisements, and you can look at only a dozen or so cases a year, then it is virtually an unregulated area," says Richard Cleland, an assistant director in the FTC's division of advertising practices.

Over the years, several bills have been proposed in Congress to give the FDA more power to take action against the offenders, including one introduced by Senators Orrin Hatch and Tom Harkin last May. So far, none has made it out of committee and been passed. Until that happens, it's up to you to keep yourself safe.

Be a cautious consumer.
If, with your doctor's okay, you take a supplement such as fish oil or calcium, look for a seal on the bottle from NSF International, the United States Pharmacopeia, or ConsumerLab.com. Note that these companies are paid by supplement makers to evaluate their products for safety, purity, and ingredient list accuracy. They don't run lengthy patient trials to ensure that the product works—but at least you know it won't be adulterated. (Better yet, choose a brand from our list of 100 Best Supplements For Women.)

Speak out about side effects.
If you've taken a supplement and experienced unexpected symptoms, the FDA urges you to report the problem to its MedWatch Safety Information and Adverse Event Reporting Program at www.fda.gov/medwatch/report.htm or by phone at (800) 332-1088. Even a few such reports can help the FDA determine where to target its efforts to best effect.

Say no to supplements.
"There's no diet supplement or drug that I know of that's safe and effective long term," says Arthur Agatston, MD. What's more, according to Steven Nissen, MD, even if you do lose weight by using a drug or supplement, research suggests that once you stop taking the product, you will gain back the weight and may be at greater risk of a heart attack or stroke. Both physicians recommend a healthy diet and regular exercise as the only sustainable way to lose weight and stay healthy. (Still not sure? See what Prevention advisor Dr. Andrew Weil has to say about weight-loss supplements here.)